ML20215C109

Requests Exemption from Requirements of 10CFR50.44(c)(3) Allowing Main Coolant Sys Vents to Be Remotely Operated from Control Room & Leaving Power Supply Breakers to motor-operated Vent Valves Open.Fee Paid

ML20215C109
Person / Time
Site:	Yankee Rowe
Issue date:	10/03/1986
From:	Heider L YANKEE ATOMIC ELECTRIC CO.
To:	Mckenna E Office of Nuclear Reactor Regulation
References
DCC-86-151, FYR-86-094, FYR-86-94, NUDOCS 8610100093
Download: ML20215C109 (3)

Text

a Telephons (617) C72-8100 TWX 710'380u7619 YANKEE ATOMIC ELECTRIC COMPANY

• 1671 Worcester Road, Framingham, Massachusetts 01701 DCC 86-151

,~AN KEE 2.C2.1 October 3, 1986 ETR 86-094 Director of Nuclear Reactor Regulation United States Nuclear Regulatory Commission Washington, DC 20555 Attention: Eileen M. McKenna, Project Manager PWR Project Directorate No.1 Division of PWR Licensing A

References:

(a) License No. DPR-3 (Docket No. 50-29)

(b) YAEC Letter to USNRC, dated October 15, 1985 (c) YAEC Letter to USNRC, dated April 30, 1985 (d) YAEC Letter to USNRC, dated June 15, 1982 (e) USNRC Letter to YAEC, dated September 14, 1983

Subject:

Request for Exemption to 10CFR50.44(c)(3)(iii)

Dear Ms. McKenna:

An exemption is requested from the requirement of 10CFR50.44(c)(3)(iii) that the Main Coolant System vents "... must be remotely operated from the Control Room." While the Main Coolant System vents at Yankee are operated from the Control Room, Reference (b) proposes a change to the plant Technical Specifications that would allow leaving the power supply breakers to the motor-operated vent valves open during normal operation. This would require an operator to leave the Control Room and close the power supply breakers in the Switchgear Room before the valves could be operated from the Control l Room. The staff reviewers of Reference (b) have stated that this does not l meet the requirement that these valves be "... remotely operable from the Control Roon."  ;

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l As stated in Reference (b), the removal of power from these valves is

! required such that a fire affecting the control circuits of these valves could not result in an inadvertent actuation of a Main Coolant System vent and the resultant loss of coolant. This design change was proposed to meet the requirements of Section III.G of Appendix R to 10CFR50 (see Reference (c) for additional information).

It is not necessary that these breakers be left closed and the control i circuits left continuously energized for the following reasons:

1. The Switchgear Room is located directly beneath the Control Room.

Direct access is available from the Control Room to the Switchgear Room following an accident that may require operation of the vents.

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l l e Director of Nuclear Reactor Regulation October 3, 1986 Attention: Ms. Eileen M. McKenna Page 2 FYR 86-094

2. Operation of the Main Coolant System vents is required to vent noncondensible gases from an intact Main Coolant System so that these gases do not expand and impact core cooling as the system is depressurized. This implies that the initiating event has been terminated and recovered from such that system cooldown and depressurization can commence in a controlled manner.

3. Operating procedures for use of the vents require that the existence of a noncondensible gas bubble inside the Main Coolant System first be verified and sized such that venting termination criteria may be established. This process provides ample time to close the vent valve power supply breakers in the Switchgear Room before the valves are actually operated.

The use of manual operator actions in the Switchgear Room for operation of the Main Coolant System vents has been previously approved by the staff.

The initial design of the Main Coolant System vents had one valve powered from a nonemergency motor control center. In response to NRC questions on the system design, Yankee specifically responded in Reference (d) that manual operator actions were required in the Switchgear Room to allow powering this valve from an emergency p3wer source. Reference (e) contains the staff's Safety Evaluation Report for Yankee's compliance to NUREG-0737. Item II.B.1, Reactor Coolant System Vents, in which the use of the nonemergency motor control center and operator actions outside the Control Room were found acceptable.

Removing power from these valves will also extinguish the valve position indicating lights on the Main Control Board. However, prior to opening the breakers, the valves will be verified closed via the position indicating lights. Once the breakers are opened, the opened and closed indicating lights both being extinguished will provide verification that the breakers are indeed open, power is removed from the circuit, and the valves are still closed.

The special circumstances of 10CFR50.12(a)(2)(ii) apply to this exemption request in that the strict interpretation of " operable from the control Room" will not serve the underlying purpose of the rule. The rule requires the vents to be oper'able from the Control Room since venting noncondensible gases from the Reactor Coolant System is an abnormal event that must be strictly controlled and monitored due to the potentially severe consequences of misuse of this capability. The Yankee vent valves are operated from the Control Room during the venting process. The need to close the power supply breakers first has no impact on their operability since the time available before these valves are needed is not critical; i.e., venting is a controlled evolution that requires stable initial system conditions, not a rapid response to an emergency situation. Additionally, strict compliance with this requirement would require the expenditure of engineering and construction resources as well as the associated capital costs which would represent an unwarranted burden on our resources without a corresponding significant increase in plant safety.

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Director of Nuclear Reactor Regulation October 3, 1986 Attention: Ms. Eileen M. McKenna Page 3 FYR 86-094 Based upon the information provided above, Yankee has concluded that the interpretation of " operable from the Control Rocm" prohibiting leaving the vent valve power supply breakers open is neither needed nor justified at Yankee Nuclear Power Station. Therefore, Yankee respectfully requests an exemption from the requirements of 10CFR50.44(c)(3)(lii) to allow leaving the vent valve power supply breakers normally open.

Fee An application fee of $150.00 is enclosed in accordance with 10CFR170.21.

Very truly yours, YANKEE ATOMIC ELECTRIC COMPANY L. H. Helder Vice President / Manager of Operation LHH/bil l

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